Aromatic thiocyanates suitable for combating insect pests



Patented a... 19, 1932 UNITED STATES PATENT OFFICE c'AnL TAUBE, or LEVERKUSEN-ON-THE-RHINE, AND HANS mtxnnrnan, or .OPLAlDEN, ennmmmnssrenons T wm'rrmor CHEMICAL COMPANY, me, or newv YORK,

1:. Y., A CORPORATION or NEW YORK' AROMA'IIC THIOCYANATEs SUITABLE FOR COMBATING INSECT PESTS K0 Drawing. Application filed November 6, 1929, Serial No. 405,276, and in Germany November 26, 1928.

The present invention relates to new aromatic thiocyanates suit-able for combating insect pests and to a process for preparing same.

The new compounds of the probable gen- 5 eral formula:

Alk

omsomz wherein Alk stands for an alkyl radicle, a: for 1 or 2 and R for hydrogen, halogen or an alkyl radicle, are prepared by heating a thioether with formaldehyde-hydrochloric acid to about 5060 C. whereby the respective,

chloro-methyl-thioether is formed and by reacting upon the latter with a thiocyanate in alcoholic solution by heating to about 50 80 C. The reactions take place according to the equations:

SCH; SICK;

v omc +H01: Hi0

CH: I H:

son. son;

orncl onions +MeCNS +MeCl on; In

The new compounds are colorless crystalline substances, insoluble 1n water, soluble in a the usual organic solvents, such as methyl and ethyl alcohol, chloroform, acetone, ben-.

zine, ether, and the like.

The new compounds are valuable insecti- 40 cides. They may be used as insecticides per se or dissolvedin appropriate solvents or in conjunction with emulsifying and wetting agents in watery suspension in the colloidal state and also in admixture with other insec- 4 ticides. The lowest efficacious percentage of the substances inquestion is 0.010%.

.T he

mode of application of the watery emulsions is by spraying the plants being infected by insect pests. For combating flies, gnats and mosquitos solutions of the new insecticides in petroleum fractions are sprayed in the rooms.

. Our invention is illustrated by the following examples without being limited thereto:

Example 1 .O.4 parts by weight of 1- methylthio 1 methyl 2 thiocyan-Inethylbenzene,

prepared from the corresponding halogen compound by decomposition with ammonium thiocyanate in alcoholic solution, melting point 55 C., are dissolved in 2 parts by weight ofacetone to which a wetting agent soluble in acetone is added, and the solution is diluted with water to 100 parts by weight.

The following table is given to demonstrate the eflicacy of this compound to plant lice (aphis) on green plants:

Percentage of eflicient substance Eflicacy to plant lice on green leaves controlled on I third day M3285 UIUIM Complete destruction without injury to the leaves. Complete destruction without injury to the leaves. Complete destruction without injury to the leaves. Complete destruction without injury to the leaves. Complete destruction without injury to the leaves.

' agent soluble in acetone is added, and the sothio4=methyl-2-thiocyanmethyl benzene the Percentage of efficient substance Efficacy to plant lice on green leaves controlled on third day 0.025 Complete destruction without injury to the leaves.

Percentage of .eflicient Efficacy to plant lice on green leaves controlled on substance thud d3 Complete destruction without injury to the leaves.

Ezmmple 3. 1 methylthio 4 chloro methyl-benzene, obtainable from p-chlorophenyl'thio methyl-ether by condensation with formaldehyde-hydrochloric acid, is heated under reflux for one hour in a methyla'lcoholic solution with an excess of ammonium thiocyanate. On diluting with water the 1 niet-hylthio 4 chloro 2 thio cyanmethyl-benzene precipitates in the form of a soon coagulating oil. When recrystallized from benzene it forms well shaped crystals showing the melting point 60 C.

The substance per se acts efficiently in a concentration of 0.5% on plant lice on cucumbcrs when emulsified with the ammonium salt of isobutylnaphthalene sulfonic acid, it combats in a concentration of 0.125% plant lice on garden roses without injury to the leaves.

Other compounds which are accessible from phcnyl-thio-ethers by condensation with tormaldehyde-hydrochloric acid and exchange of the halogen by t-hiocyanate'also act in a similar manner.

We claim:

1. In the process of preparing aromatic thiocyanates the step which comprises reacting upon a chloromethyl-benzene with ammonium thiocyanate at a temperature between 50 and 80 C. Y

2. In the process of preparing l-methylstep which comprises reacting upon l-methylthio--methyl-Q-chloro-methyl-benzene with ammonium-thiocyanate in ethyl-alcoholic solution at a temperature of 60-80 C.

3. The compounds of the probable general iorm'ula s All: Gammon wherein Alk stands for an alkyl radicle, R for hydrogen, halogen or an alkyl radicle and m stands for 1 or 2, being colorless crystalline powders suitable as insecticide, insoluble in water and soluble in the usual organic solvents.

menace 4-. The compound of the probable formula SCH:

oer-son tures.

CARL TAUBE. HANS KUKENTHAL. 

